That Wikipedia link doesn't touch on the topic of divination -- or using the pendulum to seek knowledge. You'll have to dig a bit more for that, and it sounds like you already have experience with using your pendulum. If you want more information, though, I found some wonderful tutorials on YouTube just by searching for pendulum use.
Aallee, I feel like mine lies to me too sometimes! Have you rinsed it in cold tap water and "calibrated it" -- asking it to show you the movements for "Yes" and "No"?
I find that I have to do this to "reset" it every so often. Also, if you're using it A LOT, it will kind of "burn out" and not work for awhile. You may want to take a break for a day or two.
You can also test it! Ask it a question that you don't yet know the answer to. Have you ever used your pendulum to find a lost item? I lost my favorite camera awhile back. So, I drew a (very basic) sketch of my entire apartment. I held the pendulum over each room and asked, "Is the camera here?" If I got a "No," I crossed out that room. I continued until I got a "Yes" over the outline of my bedroom. Then I narrowed it down to sections of the room. I got another "Yes" over my bed.
I thought my pendulum skills weren't up to par, as there is NOTHING near or around my bed (it's too low to fit anything underneath it), but I DID find my camera halfway under my bed, covered with extra blankets!
So, how does it work? I have no clue! Some people believe that it's spirit intervention. I'm willing to believe that. Others think that your subconscious moves it -- knowing the answers to questions that your conscious mind doesn't want to accept, or accessing subconscious information that we can't comprehend in our conscious mind.
So, maybe subconsciously, I KNEW where my camera was, and the pendulum helped me tap into that.
Keep us posted on any new developments!